From U.S. Pat. No. 4,800,328, a battery charging apparatus for an electric vehicle is known, in which the primary coil and the secondary coil are wound around a core made of ferromagnetic material, which with transformers is usually composed of a multiplicity of individual plates. This construction has a large weight and a great overall height, both of which are disadvantageous and, in particular, for the vehicle, extremely undesirable according to modern-day standards.
From DE 10 2006 048 829 A1, a system for inductively transmitting electrical energy to a magnetic levitation vehicle along its route is known, whose secondary coil is equipped with a grid-shaped unit for the guidance of the magnetic flux. This flux guide unit is produced from plastic by the pouring of a mixture of casting resin and ferrite powder into a casting mold. In the finished state of the flux guide unit, the casting mold functions as its basic body.
From WO 2010/090538 A1, a coil of a system for inductively transmitting electrical energy is known, which is wound around a flat ferrite core. This ferrite core significantly extends in the longitudinal direction beyond the ends of the coil and has two pole surfaces there, on which the magnetic flux is supposed to leave the core, perpendicular to the longitudinal direction of the coil, in order to extend from there into an area in which its second coil is found in the operation of the inductive transmission system.